Knowledge-based functional design of industrial robots

This paper presents an expert functional design model and software modeling environment for designing the architecture of industrial robots. The modeling environment comprises an integrated knowledge base, an inference engine, a working memory, and an explanation unit and is implemented in CLIPS. The functional design model is based on the authors’ behaviour-driven, function-environment-structure (B-FES) formalism, which has been tailored to meet the special requirements of industrial robot design. A universal robot template has been created and a library of typical components of a robot has been compiled. Nine customized templates were generated from the universal template. Web links to the websites of manufacturers/suppliers provide easy access to data on robot components. The architectural design solutions are assessed by a set of user-defined performance criteria, such as precision, flexibility and short cycle time. Application of the approach is demonstrated through a case study of the functional design of a printed circuit board assembly robot. The authors argue that this approach is new for configuring robots and can significantly reduce the time, effort and number of errors made.     

Potential and limits of functional modelling in the CAD process

This paper gives a survey of the beginning and newest computer-aided functional modelling by German researchers. The basic principles of functional modelling are established and a representative function model is illustrated by the example of an emergency power unit. Some important methods for computer-aided modelling according to the function model are explained in detail. Following this the limits of functional modelling are outlined by describing the working arrangements of working principles using a flowchart representation of the function structure.     

Diagnosis of multiple faults with flow-based functional models: the functional diagnosis with efforts and flows approach

This paper presents the Functional Diagnosis with efforts and flows (FDef) approach to model-based diagnosis. First, it motivates our research by considering the field of functional flow-based diagnostic techniques, pointing out some of their relevant limitations, which are overcome by FDef. Then, it summarizes and exemplifies the main FDef concepts and techniques in a tutorial way. A real-world diagnostic problem in the marine engineering domain has been used to evaluate the basic FDef engine. The paper summarizes the results of the evaluation and discusses the extensions it has prompted, i.e., the introduction of qualitative deviations of variables and the exploitation of a hierarchical representation of the functional model. The ideas proposed in FDef can be easily adapted to other flow-based modeling formalisms, such as MFM.     

Service-based manufacturing systems: modelling and control

In service-based manufacturing systems, functionalities are independently developed as services and a central engine orchestrates their integration. As industrial processes tend to be very large, and performance and productivity are expected to be maximised, there is a constant interest in providing (in-advance) quality guarantees for services interactions, which contrasts with the usual non-automated workflow design. This paper provides an alternative to enhance service orchestration capabilities using supervisory control techniques. Initially, each component (atomic and composite activities) belonging to an orchestration language is modelled as a state-machine. Then, activity models are properly combined and composed, reproducing orchestrated workflows. Finally, supervisory control is used to calculate an optimal version of the orchestrator. Practical implications of handling large state-spaces are discussed and examples are provided.     

Evaporative condenser control in industrial refrigeration systems

This paper is a result of a research project which focused on optimization of an existing industrial refrigeration system for a large two-temperature level cold storage distribution facility located near Milwaukee, Wisconsin. This system utilized a combination of single-screw and reciprocating compressors (each operating under single-stage compression), an evaporative condenser, and a combination of liquid overfeed and direct expansion evaporators. A mathematical model of the existing system was developed. The model was validated using experimental data recorded from the system. Subsequently, the model served as a tool to evaluate alternative system designs and operating strategies that lead to optimum system performance. The methods, analysis, and results presented in this paper focus on evaporative condenser sizing and head pressure control. Operating system head pressures that minimize the energy costs of the system were found to be a linear function of the outdoor wet-bulb temperature. A methodology for implementing the optimum control strategy is presented. Simulation results for the annual performance of the refrigeration system investigated in this project show a reduction in annual energy consumption by 11% as a result of the recommended design and control changes.     

Optimization of product configuration design using functional requirements and constraints

We consider the general problem of designing mechanical parts moving in contact under the influence of externally applied loads. Geometrically, the problem may be characterized in terms of a conjugate triplet, which is formed by the two shapes moving in contact and their relative motion. We show that every such triplet belongs to one or more classes of functionally equivalent designs that may be represented uniquely by maximal triplets, corresponding respectively to the two largest contact shapes that are guaranteed to contain all other possible solutions to the contact design problem. In practical terms, the proposed characterization of the contact problem enables the systematic exploration of the design space using fully defined representatives of the functionally equivalent class of parts. Furthermore, such exploration may be performed using standard tools from geometric modeling, and without assuming any particular parameterization that necessarily restrict both the design space and possible computational techniques for exploring feasible designs. Because the proposed approach supports the generation of an essentially unlimited space of design solutions for a given contact problem, it is particularly effective at the conceptual design stage. Electronic Publication     

A framework for modelling,control and supervision of poultry farming

Thermal comfort is a decisive factor in broiler chicken production, as it defines the relationship between food consumption and meat production. Temperature and humidity are major parameters for thermal balance. In spite of available automation technology, poultry farming is still dependent on an expert to observe the process and set up control parameters accordingly. Besides being inefficient, this is also uncomfortable and error-prone. This article proposes a framework for control, supervision, and decision-making in poultry farming. We initially set up a plant architecture that enables us to take advantage of emerging modern technologies, such as sensor networks, control theory, and remote monitoring, to handle temperature and humidity inside a poultry house. Then, we present the steps of modelling, synthesis, and implementation of a controller that observes events in the plant and commands the actuators in a minimally restrictive, controllable and non-blocking way, while complying with a set of operational requirements. Our final result provides a dual-channel web-based supervision system that shows the process status remotely for users and allows them to interfere with control, whenever convenient.     

A hyperstable neural network for the modelling and control of nonlinear systems

A multivariable hyperstable robust adaptive decoupling control algorithm based on a neural network is presented for the control of nonlinear multivariable coupled systems with unknown parameters and structure. The Popov theorem is used in the design of the controller. The modelling errors, coupling action and other uncertainties of the system are identified on-line by a neural network. The identified results are taken as compensation signals such that the robust adaptive control of nonlinear systems is realised. Simulation results are given.     

New modelling formalism for control programs of flexible manufacturing systems

Proposed in this paper is a modelling formalism, called the FMS control model, which is able to provide a detailed guideline for the implementation of the FMS control program (PLC program). Although, there are numerous simulation models for FMSs describing the system dynamics at the level of discrete event simulation, they cannot be fully utilised for the generation of a real control program involving sensors and actuators. Due to this, PLC programs for FMSs are usually done by the repetitive method of code writing, testing, and debugging until the control objectives are achieved. This is an error-prone and time-consuming task. The proposed FMS control model is described at the level of sensors and actuators. It can support the PLC program generation from the model. Since the FMS control model has been developed by expanding the DEVS formalism, it has a well-defined formalism. The proposed methodology has been implemented and test runs were made.     

SMAR公司现场总线控制系统System302的设计

通过对SMAR公司现场总线控制系统System302各设计环节的介绍和性能、特点分析,从经济投入和技术水平两方面说明现场总线控制系统是DCS系统的升级换代产品。     

SMAR公司现场总线控制系统System302的设计

通过对SMAR公司现场总线控制系统System302各设计环节的介绍和性能、特点分析，从经济投入和技术水平两方面说明现场总线控制系统是DCS系统的升级换代产品。     

Use of digital simulation in reliability analysis for the design of industrial process control systems

Problems of reliability evaluation in man-machine systems in industrial process control are discussed. Opportunities for wider use of digital simulation for reliability prediction of man-machine systems in the design phase are analysed. A particular cognitive model is discussed for its imminent use in reliability studies of control room operations. Expected trends in the use of existing human reliability data bases are reviewed. Unification of control room patterns and procedures in various fields of modern industry is recognized as the main factor permitting the use of human error data stores from the nuclear industry and also for other applications. Relevant restricting conditions are next specified. Finally, the main requirements for a proposed reliability predictive, simulation-based software package for system designers are specified.     

温室环境模糊控制器的设计

根据温室环境控制特点,论述了一种多变量输入输出模糊控制器的设计方法,介绍了控制系统硬件组成结构,给出了执行机构的模糊规则.该系统采用T-S模型,实现执行机构的开关量控制.在控制规则制定过程中,分两级对执行机构实行控制,兼顾系统快速性与稳定性,并将其应用于温室环境控制中.实验表明,系统响应快、超调量小、稳态误差小,控制精度满足温室植物的生长需要.     

CFD modelling of moisture evaporation in an industrial dispersed system

A methodology is presented here for the mathematical modelling of moisture evaporation in a dispersed system in an industrial tower. An empirical model using characteristic drying curves was applied to calculate moisture evaporation from a droplet and particle. A simple method was developed to calculate the agglomeration process of the dispersed phase in the drying towers, using transient functions between the initial and final particle size distributions, at the nozzle and in the final product. The developed model and simulation results were validated on the basis of industrial spray tower experiments. High instability of the airflow due to the geometry of the dryer and the construction of the air inlets was observed. The general methodology applied within this CFD model is universal, and can be applied to the scaling-up of installations for dewatering in dispersed systems in order to determine configurations of feeding systems and control the product quality and safety of the process.     

An approach to functional synthesis of solutions in mechanical conceptual design. Part III: Spatial configuration

These three papers describe an approach to the synthesis of solutions to a class of mechanical design problems; these involve transmission and transformation of mechanical forces and motion, and can be described by a set of inputs and outputs. The approach involves(1) identifying a set of primary functional elements and rules of combining them, and(2) developing appropriate representations and reasoning procedures for synthesizing solution concepts using these elements and their combination rules; these synthesis procedures can produce an exhaustive set of solution concepts, in terms of their topological as well as spatial configurations, to a given design problem.This paper (Part III) describes a constraint propagation procedure which, using a knowledge base of spatial information about a set of primary functional elements, can produce possible spatial configurations of solution concepts generated in Part II.     

模块化控制阀在工业制冷温度精确控制中的应用

出于系统安全、品质保证以及节能的需求,工业制冷需要对制冷系统的介质温度进行精确控制。当温度下限受到限制时,较高的温度控制精度往往可以有效地提高系统的能效。目前针对介质温度精确控制的方法主要有压力无关型和压力相关型2种控制方式。这2种方法都可以对介质温度进行精确控制,但在应用中也有各自的特点：压力相关型对系统中吸气压力的变化较为敏感,而压力无关型对外部负荷的变化具有较高的响应速度。     

A synthesis approach to distributed supervisory control design for manufacturing systems with Grafcet implementation

In supervisory control, computational complexity and implementation flexibility represent major challenges when a large number of local components compose a target system. To overcome these difficulties, we propose a formal approach to distributed control synthesis and implementation for automated manufacturing systems (AMS). We assume that the system is modelled with automata in a local modular fashion. Local control specifications are defined for each local subsystem by means of logical equations to construct local controllers (LCs). Then, global control specifications, stated as logical implications, are applied to the LCs, which allows synchronisation and cooperative interaction among the subsystems. This paper makes two contributions. First, it outlines a formal method for constructing minimally restrictive and deadlock-free distributed controllers (DCs). Second, it proposes a method for the interpretation of these DCs into Grafcet, which is a graphical modelling formalism widely used to design the controller’s dynamic behaviour for AMS. An experimental manufacturing system illustrates the approach.